Rock drill bits



p 5, 1 T. 5.1.. FQRSSIEN 3,339,649

ROCK DRILL BITS Filed Jan. 19, 1965 5 Sheets-Sheet 2 6 /2 w T:- I

INVENTOR. 'Icr'sten BUL henna r-t Fmssn BY p 5, 1957 T. s. L. FORSSE/N 3,339,649

ROCK DRILL BITS Filed Jan. 19, 1965 I 3 Sheets-Sheet 5 INVENTOR.

Torstpn Stig Lpnna rt Foz"s"n BY ERIC Y'. MUNSON United States Patent Office 3,339,649 Patented Sept. 5, 1967 3,339,649 ROCK DRILL BITS Torsten Stig Lennart Forssn, Klinten, Sweden, assignor to Atlas Copco Aktiebolag, Nacka, Sweden, a corporation of Sweden Filed Jan. 19, 1965, Ser. No. 426,504 8 Claims. (Cl. 175-418) ABSTRACT OF THE DISCLOSURE A rock drill bit having four radially-projecting wings, each of said wings having an inserted hardened piece forming a cutting edge, the wings each having a rearwardly-directed tapered reaming portion of considerably greater length than the depth of the wing of which it forms a rear extension; the drill having flushing fluid passages, one of which is located axially of the drill and from which radial passages extend, some of the radial passages terminating between the wings and to the rear of the forward cutting edges, and other of the radial passages terminating forwardly of the first-mentioned radial passages.

This invention relates to improvements in rock drill bits having radial wings which carry rock cutting means defining the gauge diameter of the bit at the cutting end face of the bit and having flushing fluid passages opening adjacent to said cutting means for removing the chips from the bottom of the bore hole. In deep hole drilling it often occurs that chips or small rock pieces are deposited on peripheral faces of the bit tapering rearwardly towards the central longitudinal drill bit axis and prevent or make the withdrawal of the drill rod and bit very difficult. To avoid this disadvantage it has been suggested to use so-called two-way bits which have cutting teeth directed rearwardly of the bit, or to provide reaming ribs extending along the bit for a considerable part of the length of the bit. Such well-known bits still have areas which taper rearwardly or which are formed in such a way that they are liable to collect deposits of chips or small pieces of rock when drilling is stopped. These chips or rock pieces have a tendency to form wedges between the bit and the wall of the bore hole and thereby prevent withdrawal of the drill rod and bit or make such withdrawal very difficult.

One object of the present invention is to provide a drill bit which is shaped in such a manner that it has substantially no areas or faces on which rock chipsor pieces are liable to collect or settle when a rock bit made according to the invention is stopped at the bottom of a drill hole.

A further object of the invention is to provide a drill bit of the above type which is simple to manufacture and cheap and very durable in use.

For this purpose I provide a rock drill bit of the type described having remaining bit portions extending rearwardly axially from at least two of said wings rearwardly of said cutting means at substantially the gauge diameter of the bit and tapering peripherally towards a rearwardly directed cutting edge. The reaming bit portions of this bit form a plough-like portion on which chips and debris have little or no tendency to collect. The reaming portions also help to guide the bit so that a round and straight hole may be obtained. One embodiment of a rock drill bit according to the invention together with a drill rod and a drill rod coupling are illustrated on the accompanying drawings by way of example, it being understood that various modifications are possible within the scope of the appended claims without departing from the invention.

FIG. 1 is a side view of a rock drill bit according to the invention, and FIG. 2 is an end view looking at the cutting end face of said drill bit. FIG. 3 is a longitudinal section on lines III-III and FIG. 4 a longitudinal section on lines IV-IV in FIG. 2. FIG. 5 is an end view of the drill bit according to FIG. 1 looking towards the rear end of the bit. FIG. 6 is a perspective view of a drill bit, fragmentary drill rods, and a coupling sleeve for connecting the drill rods according to the invention.

The illustrated drill bit is of the detachable type adapted to be screw-threaded on the threaded end of a drill rod and is provided with hard metal inserts forming radial cutting edges in X-shape at the cutting end face of the bit. The cutting means at the cutting end face of the illustrated bit extend radially to define the gauge diameter of the bit and are secured in radial *wings in the bit. However, other forrns of cutting means may be provided according to the invention within the scope of the following claims without departing from the idea of the invention. The illustrated bit has a hub portion 1 of generally square cross section which fomns a screw threaded socket having screw threads 2 for engaging the screw threaded end of a drill rod 3. The hub portion 1 is provided with four radial wings 4, 5, 6, 7 which extend from a center plug 8 to the gauge diameter of the bit and are provided with radial slots in which radial hard metal inserts 9 are secured in a conventional way by soldering or brazing, said inserts forming the cuttings edges 10 Which extend radially from the centre plug 8 to the gauge diameter of the bit. Reaming portions 11 extend axially rearwardly of the wings 4, 5, 6, 7, to the rear end face 12 of the bit. The reaming portions 11 have a leading edge 13' and a trailing edge 14 which tapers towards the rear end face 12 of the bit the leading edge 13 being substantially axial and the trailing edge 14 forming an angle less than 30 with the leading edge 13 and preferably about 20, as indicated in FIG. 1. The reaming portion 11 ends rearwardly in a blunt radial edge 15. Both the leading and trailing edges 13, 14 of the reaming portions 11 extend at substantially the gauge diameter so that the peripheral face of the reaming portions of the bit is substantially a cylindrical surface with little less than gauge diameter. The reaming edges 13, 14 of the reaming portions are formed asdirect continuations rearwardly of reaming edges 16, 17 of the radial wings 4-7.

The bit is provided with a central flushing fluid passage 18 which extends from the bottom surface 19 of the threaded socket formed by the hub 1. From the passage 18 two passages 20 extend to an opening in the side surfaces of the hub portion 1 in the obtuse angle between the wings 5 and 6 and 7 and 4, respectively. Two further passages 21 extend from the passage 18 to the cutting end face and open between the wings in the acute angle between the cutting inserts.

From FIG. 5 it would be obvious that the drill bit according to the invention can be manufactured from rolled stock having in cross section the general outer contour of FIG. 5 so that only very little machining has to be carried out on work pieces cut from such rolled stock. Said machining comprises substantially boring and threading of the hole forming the screw threaded socket 2, milling the cutting end face and the grooves for accommodating the hard metal inserts 9, milling a part of the hub to provide the trailing edge 14 of the reaming portion 11, and boring the various flushing fluid passages 18, 20, 21.

The above described drill bit is preferably connected to a screw threaded drill rod 3 which together with other drill rods 3 forms a drill gang in which the various drill rods are connected by means of sleeves 22, FIG. 6. Said sleeves are provided with reaming wings 23 having reaming edges 24 and 25.

The above described rock drill bit should only be considered as an example and may be modified in various different ways within the scope of the claims. The leading reaming edge 13 of the drill bit may for instance form a small angle with the axis of the bit.

What I claim is:

1. A rock drill bit having radial wings which carry rock cutting means defining the gauge diameter of the bit at a cutting end face of the bit and having flushing fluid passages opening adjacent said cutting means for removing the chips from the bottom of the bore hole, characterized by reaming bit portions extending rearwardly axially from at least two of said wings at points relatively close to the cutting end face of the bit and rearwardly of said cutting means at substantially the gauge diameter of the bit and tapering peripherally towards a rearwardly directed cutting edge.

2. A rock drill bit according to claim 1, in which each of the reaming bit portions has a leading edge directed axially of the bit and a trailing edge forming less than 30, and about 20, with said leading edge, so that each reaming bit portion is formed like a wedge.

3. A rock drill bit according to claim 1, in which each wing has a leading and a trailing edge and the leading and trailing edges of the reaming portions extend as substantially direct continuations of said leading and trailing edges of the wings and at substantially the same diameter all along the bit, said diameter being slightly less than the gauge diameter of the bit.

4. A rock drill bit having a plurality of radial wings having hardened inserts in their forward ends forming forward cutting edges, reaming portions extending rearwardly from the wings and tapering from the rear terminations of the wings to the rear end of the bit, said reaming portions being of greater length than the wings, flushing fluid passages in the drill including a passage located centrally between the wings and other passages communicating at one end with the central passage, some of said other passages forwardly terminating between the wings to the rear of the inserts and some of said other passages having their outer ends terminating forwardly of the ends of the last-mentioned other passages and close to the inserts.

5. A rock drill bit according to claim 4, in which each insert carrying wing portions (4, 6; 5, 7) has a substantially axially extending leading and trailing edge (16, 17) and each wedge-like portion has an axially extending leading edge (13) and a trailing edge (14) which intersects said leading edge (13) substantially at the rear end of the bit, said leading edges (13, 16) and said trailing edges (14, 17) being substantially continuous and extending at substantially the same bit diameter all along the bit to provide reaming edges.

6. A rock drill bit according to claim 4, in which the bit has two pairs of wings which in cross section form substantially an X, and in which flushing passages (21, 21) open radially in the obtuse chutes between said wings which extend axially all along the bit.

7. A rock drill bit having a hub portion adapted to be removably fitted to a hollow drill rod and provided with at least two pairs of radially extending wings integral with said hub portion and forming cutting end portions carrying hardened inserts at the cutting end face of the bit, said hub portion having flushing fluid passages opening adjacent said cutting end face of the bit, said bit being characterized in that at least two pairs of said radially extending wings extend axially from said insert carying portions (4, 6; 5, 7) to the rear end portion (12) of the bit and'taper peripherally from the insert carrying portions towards a rearwardly directed cutting edge (15) at the rear end of the bit, the taper being substantially between 30 and 20" so as .to form wedge-like wing portions extending from the insert carrying portions, said wedge-like portions being radially confined by a cylindrical surface (11) having substantially the same outer diameter as the gauge diameter of the bit.

8. A detachable rock drill bit having radial wings extending radially in the shape of an X to define the gauge diameter of the bit at the cutting end face of the bit and having flushing fluid passages opening adjacent said wings, and having a threaded connection portion in the rear end of said bit for attaching the bit to a hollow drill rod, said bit having along its whole length a generally X- shaped cross section with a central hub portion accommodating a flushing fluid passage; said wings providing means for carrying hard metal inserts at the cutting end face of the bit and reaming portions starting close to the forward end of the wings and tapering towards the rear end of the bit to form wedge shaped reaming portions with a leading and a trailing edge extending to little less than gauge diameter all along the reaming portions.

References Cited UNITED STATES PATENTS 54,226 4/1866 Smith 175-411 237,013 1/1881 Hammond 175-420 658,060 9/1900 'Dudley 175-401 820,530 5/1906 Strum l-419 X 2,297,983 10/ 1942 Rea 409 X 2,368,512 1/1945 Zimmerman 175418 X 2,519,861 8/1950 Turner 175401 X 2,602,641 7/1952 Wade 175-410 2,971,594 2/1961 Spencer 175-401 X 2,976,944 3/1961 Bassinger 175-410 3,128,835 4/1964 Kirker 175401 CHARLES E. OCONNELL, Primary Examiner.

R. E. FAVREAU, Assistant Examiner, 

1. A ROCK DRILL BIT HAVING RADIAL WINGS WHICH CARRY ROCK CUTTING MEANS DEFINING THE GAUGE DIAMETER OF THE BIT AT A CUTTING END FACE OF THE BIT AND HAVING FLUSHING FLUID PASSAGES OPENING ADJACENT SAID CUTTING MEANS FOR REMOVING THE CLIPS FROM THE BOTTOM OF THE BORE HOLE, CHARACTERIZED BY REAMING BIT PORTIONS EXTENDING REARWARDLY AXIALLY FROM AT LEAST TWO OF SAID WINGS AT POINTS RELATIVELY CLOSE TO THE CUTTING MEANS AT SUBSTANTIALLY THE REARWARDLY OF SAID CUTTING MEANS AT SUBSTANTIALLY THE GUAGE DIAMETER OF THE BIT AND TAPERING PERIPHERALLY TOWARD A REARWARDLY DIRECTED CUTTING EDGE. 